The present invention relates to a method and portable apparatus to be used for the spray application of chemicals on trees and other elevated vegetation, for the eradication of birds or other animals located thereon.
The removal of unwanted bird roosts from tree stands is becoming a more frequently encountered problem for land owners and governmental authorities. Large stagnant populations of birds such as starlings or blackbirds pose many hazards to property, vegetation, community health, and even airport navigation. Many methods have been attempted to remove such unwanted bird roosts, including noise generation, visual fright stimulation, removal of vegetation, and chemical spraying. By far the most successful method has been the spray application of a chemical wetting agent, mixed with water, directly on the birds. This reduces the surface tension of feather oils, allowing water to penetrate the skin, eventually chilling and killing the birds.
Unfortunately, previously known systems of chemical spraying of bird roosts, such as by helicopter or conventional irrigation-type systems, have been unsatisfactory. Usually, some amount of rainfall is needed within a 24 hour period prior to spraying so that the bird feathers will be soaked. Helicopters cannot carry enough water and chemical to accomplish this. Also, helicopter spraying cannot provide a regular spray pattern, which results in an inconsistent and incomplete bird kill. Because most bird roosts are at least eight to ten acres, helicopter spraying is expensive.
Ground-based sprinkler systems using conventional agricultural irrigation components have been used with some success. The U.S. Fish and Wildlife Service configured such a system in 1980. However, such systems are massive, using an extensive series of lateral pipes with twenty vertical risers and sprinkler heads per acre. Moreover, substantial alteration of the bird roost itself, e.g., removal of trees and vegetative ground cover, is usually necessary just to set the system up. Because of the use of multiple sprinkler heads mounted directly in the roost, the noise from the system scares off many birds before they can be effectively treated. Experience has also shown that at least four-hundred man hours are required just to set up such a system to cover only two acres. These conventional irrigation-type spray systems are limited in coverage because the components have limited spray radius and spray elevation. This is particularly true in areas of varying terrain, for which conventional irrigation-type spraying systems are unsuited. Finally, the typical cost of present systems, approximately $12,000.00, is too high to allow routine use by individuals or small government agencies.
What is needed, then, is a system for spray treating unwanted bird roosts that is low-cost, easy to set up, non-damaging to the environment, and that can cover a large area of varying terrain.